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From "Doug Cutting (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HADOOP-441) SequenceFile should support 'custom compressors'
Date Tue, 29 Aug 2006 17:19:23 GMT
    [ http://issues.apache.org/jira/browse/HADOOP-441?page=comments#action_12431296 ] 
            
Doug Cutting commented on HADOOP-441:
-------------------------------------

Overall this looks good.

On CompressionInputStream and CompressionOutputStream, the methods of FilterInputStream and
FilterOutputStream should not repeated as abstract method.  That's overly paranoid and clutters
the code, making it hard to see how this differs from a normal stream.  These should have
only an abstract resetState() method and a ctor.  It seems FilterInputStream isn't buying
much, perhaps it would be simpler to extend InputStream and OutputStream directly: that would
give you most of what you're trying to defeat in the Filter classes.


> SequenceFile should support 'custom compressors'
> ------------------------------------------------
>
>                 Key: HADOOP-441
>                 URL: http://issues.apache.org/jira/browse/HADOOP-441
>             Project: Hadoop
>          Issue Type: New Feature
>          Components: io
>            Reporter: Arun C Murthy
>         Assigned To: Arun C Murthy
>             Fix For: 0.6.0
>
>         Attachments: codec.patch
>
>
> SequenceFiles should support 'custom compressors' which can be specified by the user
on creation of the file. 
> Readily available packages for gzip and zip (java.util.zip) are among obvious choices
to support. Of course there will be hooks so that other compressors can be added in future
as long as there is a way to construct (input/output) streams on top of the compressor/decompressor.
> The 'classname' of the 'custom compressor/decompressor' could be stored in the header
of the SequenceFile which can then be used by SequenceFile.Reader to figure out the appropriate
'decompressor'. Thus I propose we add constructors to SequenceFile.Writer which take in the
'classname' of the compressor's input/output stream classes (e.g. DeflaterOutputStream/InflaterInputStream
or GZIPOutputStream/GZIPInputStream), which acts as the hook for future compressors/decompressors.

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